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Influence of iron on the occurrence of primary mullite in kaolin based materials: A semi-quantitative X-ray diffraction study

Abstract : Iron-enriched reference kaolins (KGa-1b, KGa-2 and KF) were used to study the effect of iron on the development of mullite phases during the sintering of kaolin-based materials. Up to 1050 °C, primary mullite formation occurred at earlier temperature within iron-enriched kaolins than in the case of iron-free kaolins. At 1150 °C, the presence of ferric ions tended to promote the transformation of the spinel (γ-Al2O3-like) phase into primary mullite. This action was correlated with an enhancement of the diffusion mechanism of the main constitutive species of the samples (Al, Si). In the range 1300–1400 °C, iron-enriched kaolins exhibited an abnormal grain growth of secondary mullite crystals and a partial reduction of hematite (Fe2O3) into magnetite (Fe3O4). These two iron compounds reacted with mullite and cristobalite, leading to the occurrence of eutectic liquids as expected from phase equilibrium diagrams.
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https://hal-unilim.archives-ouvertes.fr/hal-01116972
Contributeur : Fabrice Rossignol <>
Soumis le : lundi 16 février 2015 - 10:21:18
Dernière modification le : vendredi 28 février 2020 - 13:26:14

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Gisèle Laure Lecomte-Nana, Jean-Pierre Bonnet, Nibambin Soro. Influence of iron on the occurrence of primary mullite in kaolin based materials: A semi-quantitative X-ray diffraction study. Journal of the European Ceramic Society, Elsevier, 2013, 33 (4), pp.669-677. ⟨10.1016/j.jeurceramsoc.2012.10.033⟩. ⟨hal-01116972⟩

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